Lake Iliamna, Alaska — Rick Halford is a Manifest Destiny kind of Alaskan. He cleared his land with dynamite. He calls himself the “ideal redneck Republican.” As a longtime leader in the state legislature, he never met a hard rock mine he didn’t like.

That is, until he took a long look at the proposed Pebble Mine in southwest Alaska. It’s a phenomenal prospect, the biggest and richest in North America. But to dig a mine there is to make a Faustian bargain that involves an agonizing Alaskan twist.

In return for copper and gold worth an estimated half a trillion dollars, state and federal regulators risk poisoning what scientists describe as the last best place on earth for millions of wild salmon – and the risk from toxic mine waste would last forever.

“If God were testing us, he couldn’t have found a more challenging place,” said Halford, who helped write Alaska’s industry-friendly mining laws when he was president of the state senate.

Global mining giant Anglo-American and its Canadian partner, Northern Dynasty, want to dig one of the world’s largest open-pit mines — up to three miles wide and thousands of feet deep. They want to do it in the near-pristine watershed of Bristol Bay, home to the world’s largest sockeye salmon fishery.

No mine of this size – with huge dams for mine waste that would stand taller than the Washington Monument — has ever been developed in such an ecologically sensitive region.

The proposal has triggered partisan infighting that reaches from the Alaskan tundra to the halls of Congress, where House Republicans accuse the Obama administration of plotting a preemptive move to kill the mine.